London: Arsenal have proved past masters at finishing in the Premier League`s top four but manager Arsene Wenger says the task is becoming harder every season.

With 10 games remaining the Gunners are well-placed in third spot, four points behind second-placed champions Manchester City, and are closing in on an 18th successive qualification for the Champions League.

They begin their run-in at home to West Ham United on Saturday, looking for a 10th successive win against their London rivals whose early-season form has petered out.

"I like this time of the season because every game is important, it`s a period when you need composure, mental strength, focus and it`s always interesting to see how your players respond to that," Wenger told a news conference.

"It gets more difficult every year because more teams compete (for the top four) and I believe that in the future it will get even harder."

Wenger said Arsenal would not be thinking about trying to turn around their Champions League tie against AS Monaco next week until after the West Ham game.

"That`s a big game but tomorrow`s game is of the same importance," Wenger, whose side lost the first leg 3-1, said.

"We have been consistent against West Ham recently but on two or three occasions we`ve been lucky."

Lining up against Arsenal on Saturday will be their former midfielder Alex Song, who is on loan at West Ham from Barcelona, whom he joined in a 15 million pounds ($22.19 million) move from the Gunners.

"West Ham had a very strong start to the season and he was one of the influential players in there," Wenger said.

"He looks extremely focussed and motivated. I brought him here when he was 17 and I know how good he is."